#include<iostream>
#include<vector>
using namespace std;

class Solution{
    int m,n;
    int dx[4] = {0,0,1,-1};
    int dy[4] = {1,-1,0,0};
    int pre;
public:
    vector<vector<int>> floodFill(vector<vector<int>>& image, int sr, int sc, int color) {
        if (image[sr][sc] == color) return image;

        pre = image[sr][sc];
        m = image.size(),n = image[0].size();
        dfs(image,sr,sc,color);
        return image;
    }

    void dfs(vector<vector<int>>& image,int i,int j,int color)
    {
        image[i][j] = color;

        for (int k = 0; k < 4; k++)
        {
            int x = i + dx[k],y = j + dy[k];
            if (x >= 0 && x < m && y >= 0 && y < n && image[x][y] == pre)
            {
                dfs(image,x,y,color);
            }
        }
        return;
    }
};